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Géographie physique et Quaternaire
Géographie physique et Quaternaire
Evidence from Keewatin (Central Nunavut) for PaleoIce Divide Migration*
Isabelle McMartin et Penny J. Henderson
Glacial History, Paleogeography and
Paleoenvironments in Glaciated North America
Volume 58, numéro 2-3, 2004
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Isabelle McMartin et Penny J. Henderson "Evidence from
Keewatin (Central Nunavut) for Paleo-Ice Divide Migration*."
Géographie physique et Quaternaire 582-3 (2004): 163–186.
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Géographie physique et Quaternaire, 2004, vol. 58, nos 2-3, p. 163-186, 12 fig.
EVIDENCE FROM KEEWATIN
(CENTRAL NUNAVUT) FOR PALEO-ICE
DIVIDE MIGRATION*
Isabelle MCMARTIN** and Penny J. HENDERSON; Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8.
ABSTRACT Ice directional indicators were compiled from extensive
field mapping and air-photo interpretation in the Keewatin region of
central Nunavut. The profusion of multi-faceted bedrock outcrops,
intersecting striations, superimposed streamlined landforms, and
stacked till units, particularly beneath the former Keewatin Ice Divide,
is interpreted to be the result of the migration of the main ice divide in
the region, by as much as 500 km between ice-flow phases, possibly
through much of the Wisconsinan glaciation. This palimpsest glacial
landscape reflects protection under an ice divide because of lowvelocity basal sliding, and changes in flow velocity as a result of shifting ice flow centres. Relative ages of regional ice-flow sets were used
to reconstruct multiple phases of paleo-ice flows, stemming from ice
centres external to the region prior to or at LGM, and from a local ice
divide throughout deglaciation. This work refutes previous interpretations of the age and stability of the Keewatin Ice Divide, and has implications for interpreting glacial dispersal trains and for mineral exploration in Keewatin.
RÉSUMÉ Nouvelles données sur la migration d’une ancienne ligne
de partage glaciaire au Keewatin (centre du Nunavut). Des indices
d’écoulement glaciaire ont été compilés à partir d’une cartographie à
grande échelle sur le terrain et à l’aide de la photo-interprétation dans
la région du Keewatin au centre du Nunavut. L’abondance d’affleurements rocheux à facettes multiples, de stries entrecroisées, de formes
profilées superposées et d’unités de till empilées, notamment sous
l’ancienne ligne de partage glaciaire du Keewatin, est le résultat de la
migration de la ligne de partage glaciaire principale sur 500 km dans
la région du Keewatin au cours de la glaciation du Wisconsinien. Ce
paysage glaciaire est le vestige d’un glissement minimal sous la ligne
de partage glaciaire et des variations de vitesse d’écoulement causées par le déplacement des centres d’écoulement. Les âges relatifs
des familles d’écoulement glaciaire ont permis de reconstituer de
nombreuses phases glaciaires anciennes, qui sont affectées par les
centres d’écoulement situés à l’extérieur de la région et par une ligne
de partage glaciaire locale jusqu'à la déglaciation. Ces résultats réfutent les interprétations antérieures quant à l’âge et à la stabilité de la
ligne de partage glaciaire du Keewatin et ils aident à mieux comprendre les trains de dispersion glaciaire et l’exploration minérale
dans la région du Keewatin.
Manuscrit reçu le 21 juillet 2005 ; manuscrit révisé accepté le 27 janvier 2006 (publié le 2e trimestre 2006)
* Geological Survey of Canada contribution number 2005281
** E-mail address: [email protected]
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I. MCMARTIN and P. J. HENDERSON
INTRODUCTION
Recent models for inception, growth and retreat of the
Laurentide Ice Sheet propose ice accumulation and flow out of
upland areas west of Hudson Bay, on Baffin Island, and in
Quebec-Labrador, and late ice remaining longest in these same
areas (e.g. Shilts, 1980a; Boulton et al., 1985; Andrews, 1987;
Dyke and Prest, 1987; Clark et al. 1996; Dyke, 2004). Details of
ice sheet reconstructions are commonly based on patterns of
paleo-ice flow features (i.e. striations, bedforms) and distributions of glacially dispersed debris. These data, although extensive, are largely undated and, consequently, there is much discussion on the flow dynamics of the Laurentide Ice Sheet.
Evidence for the dynamic nature of ice dispersal centres is provided by extensive field measurements of multi-directional glacial striations (e.g. Kleman, 1990; Veillette et al., 1999; Veillette,
this volume), regional mapping of palimpsest glacial landforms
(e.g. Stea and Brown, 1989; Mitchell, 1994), and large-scale
compilations of glacial lineations from satellite imagery (e.g.
Boulton and Clark, 1990a; Kleman et al., 1994; Clark, 1994,
1997; Clark et al., 2000). Assessing the mobility of ice domes
and ice divides throughout the Wisconsinan glaciation has
become of critical significance for developing accurate concepts
of the history and configuration of the ice sheet, a prerequisite
for modeling past climates and earth rheology (Peltier, 1996;
Kleman et al., 2002; Marshall et al., 2002).
The Geological Survey of Canada (GSC) recently conducted
systematic mapping of ice-movement indicators over the
Keewatin region in central mainland Nunavut (Fig. 1). This new
mapping consisted of field measurement of erosional ice-flow
indicators on bedrock, compilation of glacially streamlined landforms from aerial photographs, and re-examination of glacial
stratigraphy as it relates to ice-movement chronology (McMartin
and Henderson, 1999, 2004). It builds on previous surficial mapping in the area by the GSC at 1:125 000 scale (Arsenault et al.,
1981; Aylsworth et al., 1981a, 1981b, 1981c, 1981d, 1984,
1986, 1989), and drift compositional studies at local and
regional scales (i.e. Shilts, 1971, 1973, 1977; Klassen, 1995,
2001). Prior to our recent mapping, cross-striations and streamlined landforms indicated diverse ice-flow trends but their relative ages and significance to the regional ice-flow history
remained poorly known.
This area of central Nunavut, a portion of the former District
of Keewatin of the Northwest Territories, straddles parts of the
‘Keewatin Ice Divide’, recognized and defined by Lee et al.
(1957) as a discrete dispersal centre, but essentially interpreted as a deglacial feature. Later, the Keewatin Ice Divide
was redefined as a relatively static, long-lived feature of the
Laurentide Ice Sheet (e.g. Shilts et al., 1979; Shilts, 1980a).
More recently, Boulton and Clark (1990a, 1990b) proposed a
highly dynamic Laurentide Ice Sheet with a mobile divide in
Keewatin, yet supporting the multi-domed ice sheet models
of Shilts, Dyke and others. Thus far, the history of the Keewatin
Ice Divide, and its relative stability throughout the last glaciation, is still subject to debate (e.g. Klassen, 1995; Dyke et al.,
2002), and most modelling exercises have yet to attempt to
explain ice divide migrations (e.g. Tarasov and Peltier, 2004).
In this paper we provide an ice-movement chronology in an
area of complex ice flow by integrating both glacial striations
FIGURE 1. Location map of study area in central Nunavut. The distribution of Thelon Basin and Baker Lake Basin rocks of the Dubawnt
Supergroup are shown in dark grey (from Paul et al., 2002).
Carte de localisation de la région à l’étude dans le centre du Nunavut.
La distribution des roches des bassins du Thelon et de Baker Lake faisant partie du supergroupe de Dubawnt sont montrées en gris foncé
(d’après Paul et al., 2002).
and landforms, and we re-evaluate the significance of the
Keewatin Ice Divide throughout the last glaciation. Our interpretations lead us to support a much more dynamic behaviour
for the Keewatin Ice Divide than previously realised. The results
are presented and incorporated with previous work in the area,
and discussed with respect to the the paleogeography maps of
Dyke and Prest (1987) and the recent deglaciation maps of
Dyke (2004).
REGIONAL SETTING
The study area lies near the centre of the area covered by
the Late Wisconsinan Laurentide Ice Sheet (LIS) west of
Hudson Bay (‘Keewatin Sector’: Prest, 1970). Surficial features
in the region (e.g. eskers, ribbed moraine, streamlined landforms) form a distribution pattern that is roughly concentric about
a zone mainly characterized by the absence of eskers (Fig. 2).
Till is the dominant surficial deposit and occurs as fluted and
drumlinized terrain, ribbed moraine and till blankets of varying
thickness (1-20 m). The terrain is rather featureless, consisting
of flat-lying to rolling plains with numerous lakes of varying size
commonly elongated NW-SE, parallel to the dominant regional
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165
Ukkusiksalik
National Park
Back River
W
ag
er
Schultz
Lake
Tehek
Lake
Di
vi
de
Thelon River
Ba
y
Princess
Mary Lake
Baker
Lake
Pitz
Lake
64˚N
KR-B
KR-A
Cheste
rfield
Ice
30M-A
Ke
ew
a
tin
River
Dubawnt
Lake
Kazan
Inle
t
Kaminuriak
Lake
Rankin
Inlet
Yathkyed
Lake
Kaminak
Lake
62˚N
90˚W
98˚W
Hudson
Bay
Legend
Eskers
0
km
100
Drumlins or
flutings
FIGURE 2. General location of the Keewatin Ice Divide and distribution of eskers and streamlined landforms in the Keewatin region of
central Nunavut (from Aylsworth and Shilts, 1989). Stratigraphic sections discussed in the text are shown with black triangles.
Localisation générale de la ligne de partage glaciaire du Keewatin et
distribution des eskers et des formes profilées dans la région du
Keewatin au centre du Nunavut (d’après Aylsworth et Shilts, 1989).
Les coupes stratigraphiques à l’étude sont représentées par des triangles noirs.
ice-flow direction. Relief is low, rarely exceeding 150 m, with
highest elevations at approximately 290 m asl southeast of
Princess Mary Lake and 331 m asl between Rankin and
Chesterfield Inlets (Fig. 3). The land slopes gently towards
Hudson Bay through three sub-drainage basins: Kazan, Lower
Thelon and Northwest Central Hudson Bay (Environment
Canada, 1986). Flights of raised marine strandlines occur as
high as 169 m asl in the Kaminak Lake area but regionally, the
marine limit decreases northerly from approximately 161 m
around Yathkyed Lake to 130 m west of Pitz Lake, reflecting
the distribution of remnant ice within lake basins in the area of
the Keewatin Ice Divide (Shilts, 1986). Deglaciation of the area
occurred between 7.2 and 6 ka BP (Dyke, 2004).
The study area is predominantly underlain by Canadian
Shield rocks of the western Churchill Province (Hearne
Domain), which comprise Archean gneiss terranes, supracrustal
belts and associated plutons, for the most part deformed during
the Proterozoic (Paul et al., 2002). Remnants of unmetamorphosed Proterozoic sedimentary and volcanic rocks of the
Dubawnt Supergroup outcrop in the most northwestern part of
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I. MCMARTIN and P. J. HENDERSON
FIGURE 3. Digital elevation model
within the Keewatin region of central Nunavut. Location of study
area is outlined.
Modèle numérique d’élévation
pour la région du Keewatin au
centre du Nunavut. La région à
l’étude est délimitée.
the area (Fig. 1). These rocks are lithologically distinct from the
metamorphosed lithologies of the Archean terrane (Gall et al.,
1992) and thus are useful as ice-flow indicators.
PREVIOUS RESEARCH
Previous regional ice-flow indicator mapping in the area
included the measurement of a number of ice-movement erosional features, generally with poorly defined relative chronology, mapping of glacial landforms and lineations interpreted
from aerial photographs or satellite imagery, and recognition
of glacial dispersal trains at different scales. The following is a
summary of literature related to the Quaternary geology of
the study area with emphasis on the debate over the duration
and location of the Keewatin Ice Divide.
Early interpretations of striations led Tyrrell (1897) to suggest a ‘Keewatin Glacier’ centered in the District of Keewatin
that served as one of a number of dispersal centres around
Hudson Bay. He proposed three stages in the growth and
decline of the ice sheet from centres of outflow shifting progressively to the southeast by up to 400 km. In contrast, Flint
(1943) proposed the model of a single ice dome centred over
Hudson Bay during the last glacial maximum. In the early
1950s, new field work by the GSC in the ‘barren grounds’ provided a more detailed record of ice-flow indicators in Keewatin
(Craig and Fyles, 1960; Lee, 1959; Lord, 1953, Wright, 1967).
This work led Lee et al. (1957) to recognize and define the
Keewatin Ice Divide as the zone occupied by the last glacial
remnants of the Laurentide Ice Sheet west of Hudson Bay.
Lee (1959: p. 23) stated “there is no field evidence to indicate
that the Keewatin Ice Divide was active during the initial and
maximum stages of the Wisconsin glaciation”. Later Prest et
al. (1968) summarized the work of Lee and others on the
Glacial Map of Canada, showing glacial landforms and crosscutting striae with undetermined relative ages.
The District of Keewatin was the focus of an extensive driftprospecting program in the mid-1970s by the GSC. Ice-movement indicators demonstrating pervasive ice flow towards
Hudson Bay and a long dispersal train of red Dubawnt lithologies extending to the Hudson Bay coast was used to infer stability and longevity of the Keewatin Ice Divide (e.g. Shilts et al.,
1979; Kaszycki and Shilts, 1979, 1980). Shilts (1980a) argued
that the distance of glacial transport and time constraints
required to produce the Dubawnt dispersal pattern reflected a
sustained southeastward ice flow over the region throughout
one or more glacial stades of the Wisconsinan glaciation.
Nonetheless, evidence for an earlier southward flow across
Keewatin was recognized from striations and southward transport of erratics (e.g. Lord, 1953; Lee, 1959; Shilts, 1973;
Cunningham and Shilts, 1977). This was used by Cunningham
and Shilts (1977) to suggest a southeastward migration of the
ice divide, an idea originally proposed by the pioneering work
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EVIDENCE FROM KEEWATIN (CENTRAL NUNAVUT) FOR PALEO-ICE DIVIDE MIGRATION
of Tyrrell (1897). Cunningham and Shilts (1977) also reported
late striations indicating northwestward and westward flows
northwest of an arcuate zone extending through Forde and
Pitz Lake in the northwest part of the study area (“last position
of Keewatin Ice Divide” on their Fig. 1, p. 311).
Based on air-photo interpretation, and some ground observation mainly in Keewatin, Aylsworth and Shilts (1989) used a
compilation of landforms and materials for the northwestern
Canadian Shield to provide a regional interpretation of constructional glacial landforms around the Keewatin Ice Divide
(cf. Fig. 2). These authors characterized the divide as a broad
area with low-relief hummocky moraine, few streamlined landforms and no dendritic esker systems. They placed the divide
in a curvilinear zone extending northeastward in Keewatin,
consistent with the 8.4 14C ka Keewatin Ice Divide of Dyke
and Prest (1987). In contrast to Dyke and Prest (1987) though,
Aylsworth and Shilts (1989: p. 3) reported that “although the
dispersal centre had migrated eastward and southward, (...),
it probably migrated no more than 100 km”.
Despite the acceptance of the last general position of a
divide in the region, refinements of its dynamics have continued. In the 1990s, Boulton and Clark (1990a, 1990b) used
satellite imagery over North America to reveal crossing drift lineations, namely in the area of the Keewatin Ice Divide, and
to infer mobility of outflow centres within the Laurentide Ice
Sheet throughout the last glacial cycles. Based on till composition near Baker Lake, Klassen (1995, 2001) showed strong
evidence for southeastward dispersal under the Keewatin Ice
Divide area, hence supporting the southeastward migration
of the divide. Based on the examination of stratigraphic sections of till along the Kazan River, Klassen (1995) observed differences in provenance related to changes in the location and
orientation of the Keewatin Ice Divide, but he also reported
that correlations with overburden drill-core information in the
area (i.e. Shilts, 1980b) remained unclear. The preservation of
“old landforms” in Keewatin revealed from Landsat imagery
and aerial photographs was used by Kleman et al. (2002) to
infer a cold-based thermal regime and a dome in northern
Keewatin during ice sheet build-up. Detailed striation measurements north of Baker Lake led Utting and McMartin (2004)
to identify a rotation of the Keewatin Ice Divide from an
east-west to a more northeast-southwest orientation. Based
on cross-cutting striations and superimposed landforms in the
Schultz Lake area, McMartin and Dredge (2005) suggested
that much of the glacial landscape at Schultz Lake was related
to older flows, older than the Keewatin Ice Divide itself, hence
indicating mobile, wet-based ice and a transitory ice divide in
the region during the last glaciation.
METHODOLOGY
The determination of paleo-ice flow patterns in the study
area included the measurement of the orientation of smallscale glacial features on bedrock such as glacial striae and
grooves. Field observations were made from over 800 sites
in 1997, 1998 and 1999 between latitudes 62° and 64 °N and
longitudes 92° and 98 °W. Figure 4 shows a compilation of
the detailed striation measurements (small arrows). Summary
arrows shown on Figure 4 give a local interpretation of the
167
underlying data in terms of relative age, general direction and
spatial continuity (cf. section below). The complete datasets
and more detailed maps are available digitally in McMartin
and Henderson (2004). Many rock surfaces inscribed with two
or more sets of crossing striae were observed, particularly
under the area of the former Keewatin Ice Divide (Fig. 5). To
unravel the sequence of events, it was imperative to sort out
the sense of ice flow and the crosscutting relationships of
facets and striae. The sense of flow was determined from crag
and tail relationships of various scales, stoss-and-lee topography, crescentic gouges, chattermarks, and roches moutonnées (Fig. 6). Relative ages of striated facets were determined
(where possible) by evaluating their relative positions at the
outcrop scale (Fig. 7) (cf. Lundqvist, 1990; Stea, 1994).
Existing surficial geology maps for the study area (Arsenault
et al., 1981; Aylsworth et al., 1981a, 1981b, 1981c, 1981d,
1984, 1986, 1989) provided an extensive database of subglacial bedforms such as drumlins, flutings and crag-and-tails,
and other landform indicators of paleo-flow (i.e. esker, ribbed
moraine, etc.). In light of the new erosional observations on
bedrock, landforms were systematically re-mapped in 2003 by
air-photo interpretation. Previously unrecognized landforms
and many cross-cutting and superimposed streamlined landforms were recognized (Fig. 8). These are combined on
Figure 9 with all the landforms derived from existing maps.
The study of till stratigraphy in naturally exposed sections
was used to provide additional evidence of change in provenance associated with the ice-flow record. One till section
exposed along a stream west of Pitz Lake and two multiple-till
sections along the Kazan River south of Baker Lake were
examined (see Fig. 2 for location). Detailed observations of
the three sections were gathered on colour, texture, sorting,
structure, lithology, and clast fabric. Samples were collected at
about 50 cm intervals for lithologic and geochemical analysis
(McMartin and Henderson, 2004).
SEQUENCE OF ICE FLOWS
The record of successive paleo-ice flows is revealed by
cross-striations, lee-side preservation of old striations, and
cross-streamlined landforms. It is extensive and complex
across the entire region, indicating large-scale patterns of icesheet flow and their changes through time. Based on (1) the
regional association of striation sets having similar or continuous trends and the same relative age relationships (cf. Fig. 4),
and (2) analogous cross-cutting relationships between landforms (if preserved), a sequence of regional glacial flowlines
regrouped into ice-flow sets (cf. Clark, 1994) was established
for the study area (Fig. 10). Below we present an interpretation
of the relative sequence of flow changes in chronological
order, from the oldest recognized ice flows thought to have
occurred prior to deglaciation, to the most recent flow(s)
related specifically to deglaciation of the Keewatin region.
PRE-DEGLACIAL ICE-FLOW SETS
Southwesterly flows
The earliest flows recognized in the study area are to the
southwest (Fig. 10A). The evidence is subtle but found across
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I. MCMARTIN and P. J. HENDERSON
A
1
FIGURE 4. Relative ice-flow sequence determined from the crossstriation record (1 = oldest) of the study area. Large arrows represent
the local interpretation of the detailed striation measurements (small
arrows) collected recently (n = 814 sites) or reported in previous work
(n = 86 sites). The general ice flow directions are grouped by relative
ages and spatial continuity. Relative chronology at each outcrop is
available in McMartin and Henderson (2004).
Séquence relative de l’écoulement glaciaire dans la région à l’étude
déterminée à partir des stries entrecroisées (1 = plus anciennes). Les
grandes flèches représentent l’interprétation locale des mesures
détaillées des stries (petites flèches) observées récemment (n = 814
sites) ou déjà publiées (n = 86 sites). Les directions générales de
l’écoulement glaciaire ont été regroupées par âge relatif et selon leur
continuité spatiale. La chronologie relative déterminée à chaque
affleurement est disponible dans McMartin et Henderson (2004).
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EVIDENCE FROM KEEWATIN (CENTRAL NUNAVUT) FOR PALEO-ICE DIVIDE MIGRATION
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B
C
he
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rfie
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I. MCMARTIN and P. J. HENDERSON
A
B
FIGURE 5. Beneath the former Keewatin Ice Divide area, ice-flow
direction changed almost 180° between phases. Distinctive outcrops
were produced. (A) Multi-faceted outcrops forming small trigonal pyramids are common in the Yathkyed Lake area. The pyramidal shape is
the result of glacial erosion from three divergent ice-flow directions.
Two of the truncated surfaces are commonly well striated.
(B) Opposing roches moutonnées indicating ice flow to the WNW and
to the ESE on a small island in Thirty Mile Lake. The surfaces bear
striae and rat tails of opposite sense on this composite landform.
Sous l’ancienne ligne de partage glaciaire du Keewatin, la direction de
l’écoulement glaciaire a varié de presque 180° entre chaque phase
d’écoulement. Des affleurements rocheux distinctifs ont été produits.
(A) Des affleurements à facettes multiples formant de petites pyramides trigones dans la région du lac Yathkyed. La forme pyramidale
résulte de l’érosion glaciaire dans trois directions divergentes. Deux
des surfaces tronquées sont généralement bien striées. (B) Roches
moutonnées opposées indiquant des écoulements glaciaires vers
l’ouest-nord-ouest et l’est-sud-est sur une petite île au lac Thirty Mile.
Les surfaces comportent des stries et des queues-de-rat indiquant
une direction opposée sur cette forme composite.
the entire area with isolated deep striae and grooves trending
209° to 236°. In addition, early south-southwesterly striations
(183°-202°) were measured at a few sites. Early striations indicating a southwest flow have been reported within maps adjacent to the study area (Cunningham and Shilts, 1977; Schau,
1981; McMartin and Dredge, 2005), along the Dubawnt River
(Tyrrell, 1897), in the Back River area (Taylor, 1956), and as far
north as Wager Bay (McMartin and Dredge, 2005) and perhaps Committee Bay (Little, 2001). Early southwesterly glacial
landforms were not observed in the study area although
Boulton and Clark (1990a, 1990b) recognized relict southwesterly oriented drift lineations directly north of the area.
same direction as nearby old southerly striations lead us to
suggest that some relict bedforms in the study area can be
attributed to this ice-flow event. Boulton and Clark (1990a,
1990b) showed early drift lineations oriented south-southeast
in the study area.
There is little indication of southwestward glacial dispersal
in central Nunavut, except perhaps Schau (1981) who found
some evidence for glacial transport of erratics (<10 km) to the
southwest of an outcrop of calc-silicate and marble rocks north
of Baker Lake.
South-southeasterly flow
The second oldest event indicates ice flow towards the
south-southeast (Fig. 10A). Ice flow during this event is slightly
divergent and recorded by early striations and grooves trending
154° to 181°, more pervasive around Kaminak Lake and along
Hudson Bay (Fig. 4). This broadly southerly flow was recorded
in the region at a few sites (Tyrrell, 1897; Lord, 1953; Lee, 1959),
and old southward striations appear occasionally on GSC
1:125 000 scale surficial geology maps covering the area
(Arsenault et al., 1981; Aylsworth et al., 1984). Cunningham
and Shilts (1977) and McMartin and Dredge (2005) reported
early southerly striations in the Baker Lake and Schultz Lake
areas. At least a dozen streamlined landforms trending in the
Evidence for southward glacial transport in the region is not
obvious, although Cunningham and Shilts (1977) observed
erratics of quartzite of presumed Early Proterozoic age
(“Aphebian” in text) around Pitz Lake, which they interpreted to
indicate a major period of southward transport from the Schultz
Lake area. However, outcrops around Pitz Lake include basal
conglomerates of the Thelon Formation (Dubawnt Supergroup)
that contain cobble to pebble-size rounded quartzite clasts,
originally derived from local quartzite bedrock of both
Proterozoic and Archean ages (Hadlari et al., 2004). The dispersal of Dubawnt erratics as far south as the Manitoba border
(Shilts et al., 1979) provides a better support for southward
glacial transport in the region. Geochemical composition of till
collected in the lower parts of drill core south of Pitz Lake also
point to an early southward flow (Klassen, 1995).
Easterly flow
The third oldest regional event was east-southeastward
(Fig. 10A). Evidence for this parallel flow is regionally extensive
but generally less well preserved than the southerly flow. Deep
striae and grooves trending 94° to 122° are found at several
sites. This flow has never been directly reported in the study
area although Nadeau and Schau (1979) observed roches
moutonnées and red erratics north of Chesterfield Inlet, providing evidence for a pervasive eastward flow preceding the
last south-southeastward flow in that area. It is not certain
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A
B
C
D
FIGURE 6. (A) Delicate striae preserved on mafic volcanic rocks south
of Yathkyed Lake. The sense of flow (northward; to the upper right of
photo) is derived from miniature whaleback forms. (B) Roche moutonnée indicating ice flow towards the SE (to the upper left of photo)
in the Rankin Inlet area. (C) Large rat tail indicating ice flow towards
the SE (top of photo) south of Rankin Inlet. Scale is 7 cm long.
(D) Deep striae, gouges and crescentic fractures north of Kaminak
Lake indicating ice flow towards the SE (top of photo).
171
(A) Stries fines préservées sur des roches volcaniques mafiques au
sud du lac Yathkyed. Le sens de l’écoulement (vers le nord; coin supérieur droit de la photo) est déterminé à partir de petites formes en
dos de baleine. (B) Roche moutonnée indiquant un écoulement glaciaire vers le sud-est (coin supérieur gauche de la photo) dans la
région de Rankin Inlet. (C) Grande queue-de-rat indiquant un écoulement glaciaire vers le sud-est (haut de la photo) au sud de Rankin
Inlet. L’échelle fait 7 cm de long. (D) Stries profondes, broutures et
marques en croissant au nord du lac Kaminak indiquant un écoulement glaciaire vers le sud-est (haut de la photo).
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A
B
FIGURE 7. (A) Opposing sets of striations south of Kaminuriak Lake.
Deep striae and small crag-and-tails in bedrock indicating ice flow
towards the NNW (1) are preserved on the lee surface (south) of an
outcrop noticeably striated to the SE (2), creating a bevelled facet.
(B) Sets of striations preserved on a large island south of Rankin Inlet.
Deep striae and grooves indicating ice flow towards the SE (1) are
preserved on the gently sloping lee-side of surfaces striated towards
the ESE (2). This relationship is thought to reflect late glacial ice flow
associated with lobate ice-front positions.
(A) Stries opposées au sud du lac Kaminuriak. Des stries profondes
et de petits crag-and-tails rocheux indiquant un écoulement glaciaire
vers le nord-nord-ouest (1) sont préservés sur la surface aval (sud)
d’un affleurement manifestement strié vers le sud-est (2), formant
ainsi une facette biseautée. (B) Stries préservées sur une grande île
au sud de Rankin Inlet. Des stries profondes et des cannelures indiquant un écoulement glaciaire vers le sud-est (1) sont préservées
sur la pente descendante du côté aval de surfaces striées vers
l’est-sud-est (2). On pense que cette relation reflète un écoulement
glaciaire tardif associé à des positions lobées de la marge glaciaire.
however whether this eastward flow corresponds in age with
the old eastward flow reported here. Although several eastward trending glacial landforms occur in the study area
(Fig. 9), we cannot attribute an old age to any of them with
confidence. In fact, our observations lead us to ascribe a late
deglacial age for most of them (see below). Boulton and Clark
(1990a, 1990b) recognized east-southeast trending largescale drift lineations in the study area and in areas further
north, but found no direct evidence for their relative age.
the lowest till (unit D) is separated from the overlying unit by
stratified sediments and a sharp colour change (Fig. 11). The
relative proportion of Dubawnt clasts is high in relation to
greenstone/plutonic lithologies, and several base metal concentrations are low in that unit (e.g. Pb, Zn), suggesting transport over Dubawnt lithologies and, hence, an easterly direction
of glacial transport. Clast fabrics in this unit are weak but the
relative chronology interpreted from striations measured on
outcrop exposed across the river is consistent with an early
eastward flow (Fig. 11).
Till stratigraphy along the Kazan River led Klassen (1995)
to suggest an early eastward flow in the region (Lower till at his
section KC, p. 50). Examination of two Kazan River sections
(KR-A and KR-B) indicates at least three distinctive till units,
of which the lowest till is thought to have a provenance from
the west (McMartin and Henderson, 2004). At section KR-A,
Southeasterly flows
Evidence for old (i.e. pre-deglacial) southeasterly flows
occurs sporadically over much of the area, mainly in the striation
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record (Fig. 4, SE(1)). These older flows are divided here in two
sets on the basis of their relative age relationship with northerly
flows (described below): (1) southeast flows pre-dating northerly
flows, occurring north of Kazan River (Fig. 10A, SE(1)), and
(2) southeast flows post-dating northerly flows, recognized
essentially south of Kazan River (Fig. 10A, SE(2)), and only differentiated from later convergent southeasterly flows when
occurring at significantly different directions (cf. Fig. 10B).
The first set is indicated by old striations trending 125° to
144°, commonly superimposed by north to northwesterly striations (Fig. 10A). Well developed crag-and-tails that can be
associated with this early southeastward flow occur mainly
between Princess Mary Lake and Pitz Lake, and the composition of till and underlying striations on bedrock at section
30M-A west of Pitz Lake suggest it was a pervasive erosional
ice-flow event (McMartin and Henderson, 2004). North of Pitz
Lake, ancient southeasterly trending striations and relict cragand-tail landforms observed as far north as Schultz Lake attest
to the extent of this paleo-ice flow (Cunningham and Shilts,
1977; McMartin and Dredge, 2005).
The second set indicates a nearly parallel flow with striations, grooves and rare roches moutonnées trending 134° to
145°, crosscutting northerly striations (Fig. 10A). At several sites
in the Yathkyed Lake area, two or three sets of striations record
a progressive counter-clockwise shift from southeastward to
eastward, indicating this old southeastward set is closely linked
in age with the deglacial convergent ice flows (see below).
Indeed, this sequence is reversed in the Chesterfield Inlet area,
where the striation record indicates a clockwise shift from southeastward to a more southerly direction.
The principal direction of glacial transport in surface till
across the study area is southeastward (Shilts, 1973; Ridler
and Shilts, 1974; DiLabio, 1979; Shilts et al., 1979; Coker et
al., 1992; Henderson, 2000; Klassen, 1995, 2001; McMartin,
2000; McMartin et al., 2003a). Although few till provenance
studies were completed west of Kazan River, glacial transport
in directions other than southeastward was shown to be limited in the Pitz Lake area (Klassen, 1995). Moreover, glacial
stratigraphy along the Kazan River east of Pitz Lake indicates
that surface till was largely deposited by ice flow to the southeast, presumably during this event (Klassen, 1995). Likewise,
at both sections along the Kazan River (KR-A and KR-B), the
two upper tills (units A and B) have a relatively low percentage
of Dubawnt lithologies, a high percentage of greenstone/
plutonic lithologies, and high base metal concentrations, compared to lower diamicton unit(s) (Fig. 11). This composition indicates a provenance in the crystalline terrane outcropping north
of the two sites. Till fabrics at both sections vary in strength,
but suggest southeasterly (unit B) and south-southeasterly
(upper till – unit A) ice flows (McMartin and Henderson, 2004).
Northerly flows
A regional-scale flow reversal is recognized in the western
portion of the study area with persistent north to north-northwestward erosional ice-flow indicators (334°-006°) (e.g. Fig. 6A),
as far east as Kaminuriak Lake (Fig. 10A). In the same area,
numerous outcrops are moulded in two opposite directions,
sometimes three, forming small trigonal pyramids (Fig. 5A).
173
North-northwesterly striations are commonly found protected on
lee-side surfaces of outcrops glacially moulded to the southeast (cf. Fig. 7A), indicating they pre-date the latest southeasterly flows south of Kazan River. Scattered old northward striations were reported earlier in the Yathkyed Lake area by Tyrrell
(1897), Lord (1953) and Coker et al. (1992), and they are abundant in the entire Schultz Lake map area to the north (McMartin
and Dredge, 2005). Streamlined landforms that can be associated with this north-northwesterly flow are abundant in the western part of the study area (Fig. 9). They form large relict drumlins and crag-and-tails, occasionally superimposed or
crosscutted by more recent landforms (Fig. 8A). Locally, north
and west of Kazan River, there is evidence that the north-northwestward flow later shifted to the northwest (317°-334°), as
indicated by cross-striations and cross-streamlined landforms
(Fig. 10A). A similar counter-clockwise rotation in ice-flow trends
was reported north of the study area (Utting and McMartin,
2004; McMartin and Dredge, 2005).
Evidence for northward glacial transport is indicated by the
presence of distinctive Proterozoic dolomite boulders over the
Yathkyed greenstone belt derived from Hurwitz Group outcrops to the south (McMartin and Henderson, 1999). In
Section KR-A, a thin diamicton unit (unit C) shows a marked
increase in total Dubawnt clasts, specifically in arkosic sandstone (McMartin and Henderson, 2004), indicative of a very
local provenance (Fig. 11). This, together with the clast fabric, suggests this unit was likely deposited during a northerly
ice-flow event. Compelling evidence for northward dispersal
was also recently found in the Schultz Lake map area to the
north with the distribution of Thelon sandstone and dispersal
of Dubawnt volcanic clasts from the Baker Lake Basin
(McMartin et al., 2006).
DEGLACIAL ICE-FLOW SETS
Dubawnt Lake ice stream flow
A highly convergent flow pattern of late striations and
streamlined landforms trending west to northwest occurs in the
northwestern portion of the study area (Fig. 10B). The flow pattern extends back to the Keewatin Ice Divide area, and slightly
beyond (cf. Fig. 2). Striations trending 270°-326° in this area
are superimposed on all of the other flow-sets described above,
indicating that the convergent flow represents the last major
active flow in this area. Associated westerly to northwesterlytrending short and/or narrow drumlinoid features are commonly
superimposed on large drumlins and crag-and-tail landforms
indicative of northward flow (Fig. 8A). This flow set is only postdated south of Kazan River and around Yathkyed Lake by
deglacial southeasterly flows, and locally by an opposite easterly flow near Pitz Lake (see below). McMartin and Dredge
(2005) mapped the abrupt northern limit of the westerly iceflow indicators immediately south of Schultz Lake. We believe
this ice-flow pattern is part of the convergent onset zone of the
Dubawnt Lake ice stream that extends westerly into the higher
portions of the Thelon River basin as far as longitude 106 °W
(Stokes and Clark, 2003). These authors suggested the ice
stream operated during deglaciation 9-8.2 ka BP and that the
ice-stream lineaments were produced isochronously, providing
a snapshot view of the ice-stream bed immediately prior to
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A
N
FIGURE 8. Stereograms of intersecting streamlined landforms in the
area of the former Keewatin Ice Divide (within NTS 65P, see Fig. 9
for location). (A) West of Forde Lake, large drumlins indicative of northward ice flow are superimposed by flutings and crag-and-tails formed by the northwestward convergent flow of the Dubawnt Lake ice
stream. (B) Intersecting landforms indicating nearly opposite flows
south of Kazan River. Opposing crag-and-tails originate from the same
crag (shown as a circle) at several sites. Although landforms associated with the north-northwestward flow are best preserved, the relative age of striations measured on nearby outcrops suggests that southeastward flow was last in this area. Arrows represent crag-and-tails
and straight lines represent other glacial lineations in till. (Source:
Aerial photographs A14887 85-86 (A) and A14703 7-8 (B); National
Air Photo Library, 1955, 1:58 000 scale).
Stéréogrammes de formes profilées entrecroisées dans la région de
l’ancienne ligne de partage glaciaire du Keewatin (à l’intérieur de
SNRC 65P, voir Fig. 9 pour la localisation). (A) À l’ouest du lac Forde,
de longs drumlins indiquant un écoulement glaciaire vers le nord sont
superposés par du till cannelé et des crag-and-tails formés par un
écoulement glaciaire convergent vers le nord-ouest faisant partie du
courant glaciaire du lac Dubawnt. (B) Formes du relief entrecroisées
indiquant des écoulements opposés au sud de la rivière Kazan. Des
crag-and-tails opposés émanent du même nez rocheux (montré par
un cercle) à plusieurs endroits. Même si les formes du relief associées à l’écoulement vers le nord-ouest sont les mieux préservées,
l’âge relatif de stries mesurées sur des affleurements adjacents suggère que l’écoulement vers le sud-est était le plus récent dans cette
région. Les flèches représentent les crag-and-tails et les lignes droites
les autres linéaments glaciaires dans le till. (Source : Photographies
aériennes A14887 85-86 (A) et A14703 7-8 (B); Photothèque nationale de l’air, 1955, échelle 1:58 000).
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EVIDENCE FROM KEEWATIN (CENTRAL NUNAVUT) FOR PALEO-ICE DIVIDE MIGRATION
175
B
N
shut-down. Although there is currently no evidence for glacial
transport in a westerly to northwesterly direction in the northwest part of the study area, current work on till provenance in
the Schultz Lake area suggests some westerly dispersal from
the Baker Lake Basin (McMartin et al., 2006).
Local easterly flow
Late striations trending 88°-111° and streamlined landforms
indicative of an easterly flow are found locally on either side of
Thirty Mile Lake and west of Pitz Lake (Fig. 10B). Below a 6 m
high till section immediately south of Pitz Lake, striae, crescentic fractures and stoss-and-lee microtopography indicate an
easterly flow (McMartin and Henderson, 2004). At two sites
20 km north of Pitz Lake, well defined, late easterly striations
were found on glacially shaped outcrops (McMartin and Dredge,
2005). These ice-flow indicators are opposite to and post-date
the Dubawnt Lake ice stream set (cf. Fig. 5B), indicating a late
inversion of ice flow within a local remnant ice mass.
Southeasterly convergent flows
Over most of the study area (essentially southeast of
Kazan River and Pitz Lake), dominant striations, grooves and
roches moutonnées range from eastward to southward
(95°-178°) (Fig. 4, SE(2); Fig. 6B-D), indicative of convergent
ice flows to the southeast from the Keewatin Ice Divide area
(Fig. 10B). Streamlined landforms follow this regional trend
and occur over much of the area (Fig. 9), except within a central linear zone over the Kaminuriak Lake basin, and on either
side of Chesterfield Inlet where drift is thin and bedrock is principally composed of coarse-grained orthogneisses (Paul et
al., 2002). Convergence of flowlines is presumed to be a result
of ice divide geometry and reflects the arcuate configuration
of the last position of the divide in this area (i.e. concave
towards Hudson Bay). Although the flowlines are depicted as
a continuous flow set on Figure 10B and thereby assumed to
be part of one population, we find strong evidence suggesting
they formed time-transgressively as the ice front retreated.
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A
FIGURE 9. Map of streamlined landforms (drumlins, flutings and cragand-tails) compiled from existing surficial maps (n = 3 900) or recently
interpreted from aerial photographs (n = 4 401) of the study area
(modified after McMartin and Henderson, 2004). Small boxes in NTS
65P indicate the location of Figures 8A and 8B.
Carte des formes profilées (drumlins, flûtes et crag-and-tails) compilées à partir des cartes de la géologie de surface existantes ou récemment interprétées à l’aide de photographies aériennes de la région
d’étude (tiré de McMartin et Henderson, 2004). Les boîtes dans le
secteur NTS 65P montrent l’emplacement des figures 8A et 8B.
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B
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I. MCMARTIN and P. J. HENDERSON
FIGURE 10. Summary of ice-flow
patterns in study area and corresponding ice-flow directions derived
from both the erosional and depositional records. (A) Pre-deglacial
ice-flow sets in chronological order
and direction of glacial flow.
(B) Deglacial ice-flow sets, and late
deglacial ice flows related to pulling
towards esker tunnels or calving
bays.
Synthèse des patrons d’écoulements glaciaires dans la région à
l’étude et directions associées de
l’écoulement dérivées à la fois des
indices d’érosion et des formes de
déposition. (A) Familles d’écoulement glaciaire antérieur au retrait
glaciaire, en ordre chronologique
et selon la direction de l’écoulement. (B) Familles d’écoulement
glaciaire reliées au retrait glaciaire
ainsi que les écoulements glaciaires tardifs reliés à l’appel de la
glace vers les tunnels d’esker ou
vers des baies de vêlage.
A
B
Deglacial ice-flow sets
Dubawnt Lake
ice stream
Easterly flow
Convergent
SE flows
Local, late ice-flows
The patterns of ice-flow features appear disjointed in many
areas, show cross-cutting of bedforms and are not consistently
parallel (Fig. 9), indicative of a time-transgressive imprint that
is continuously reorganized during margin retreat (cf. Clark,
1999). Further evidence is provided by superimposed DeGeer
moraines at oblique angles to the well-preserved streamlined
landforms, suggesting retreat direction was not always parallel
to the regional direction of ice flow. In a number of these areas,
streamlined landforms are also reoriented obliquely to the
regional southeastward ice-flow direction, either to the
east-southeast or to the south-southeast (cf. Fig. 9), producing
a complex pattern of ice-flow patterns that can be easily confused without regional mapping and field work. Late deglacial
striations associated with lobate ice front positions in contact
with marine waters are found in several areas below about
Eskers
100 m asl, namely where marine calving bays probably moved
up Rankin Inlet and Chesterfield Inlet (Fig. 10B). Moreover,
near large continuous eskers (<3-4 km on either side), the latest striations can be found at pronounced angles to the esker
ridge, suggesting lateral movements of ice towards the esker
tunnel (Fig. 10B; cf. Repo, 1954).
PALEO-ICE FLOW HISTORY
We have presented above a relative chronology for the iceflow sets and assigned most of them a pre-deglacial age. The
Dubawnt ice-stream flow, and the time-transgressive convergent flows into Hudson Bay, are clearly believed to be deglacial
flows. Because we have no indication of the absolute ages of
the other ice-flow sets, it is not clear if the pre-deglacial flows
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179
0
100
200
A
300
400
B
Depth (cm)
500
600
700
C
800
900
1000
4
1100
1200
D
1300
1400
1500
1600
5
FIGURE 11. Lithological and geochemical composition of till at section
KR-A along the Kazan River (see Figure 2 for location) (modified after
McMartin and Henderson, 2004). Contour Schmidt equal-area nets
(lower hemisphere) show clast orientations. The mean vector (V1),
the strength of the principle eigenvector (S1) and the number of measurements (N) are indicated. Striations measured on bedrock exposed
across the river from the section are also shown (1 = oldest).
Composition lithologique et géochimique du till à la coupe KR-A le
long de la rivière Kazan (voir figure 2 pour la localisation) (d’après
McMartin et Henderson, 2004). Les stéréonets de Schmidt à aire
égale (hémisphère sud) montrent l’orientation des cailloux. Le vecteur
moyen (V1), la force du vecteur caratéristique (S1) et le nombre d’observations (N) sont indiqués. Les stries mesurées sur un affleurement rocheux situé de l’autre côté de la rivière en face de la coupe
sont aussi représentées (1 = plus anciennes).
were formed entirely during the Wisconsinan glacial period or
whether they include palimpsests of earlier glaciations. In conjunction with geological data gathered in surrounding areas
and work in progress, we now group the ice-flow sets into
phases of ice flow for the Keewatin region, propose ice divide
positions, and compare them with existing ice-sheet reconstruction models (Fig. 12).
(Fig. 12). Boulton and Clark (1990b) suggest an early outflow
centre in northeast Keewatin or northern Baffin Island, which
agrees with the old southwestward flow presented here. These
authors tentatively attribute southwesterly oriented drift lineations to the earliest Wisconsinan ice-sheet expansion (Flow
stage A, p. 338). Likewise, Kleman et al. (2002) place an outflow centre over Baffin Island and the Melville and Boothia
peninsulas, expanding into Keewatin at 90-84 ka BP. Given
that the position of the ice divide during Phase A is considerably different than that proposed for following phases, it seems
probable that Phase A predates the last glacial maximum
(LGM), and occurred during the Early-Mid Wisconsinan, or
during a previous glaciation.
PHASE A
Early flows to the southwest across Keewatin, and perhaps
as far north as Committee Bay, may have dispersed from a
centre located northeast of the study area within mainland
Nunavut, or farther north, maybe as far as Foxe Basin
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I. MCMARTIN and P. J. HENDERSON
B
A
C
D
?
?
PHASE B
Phase B reflects a major southern expansion of ice across
the study area, and is presumably responsible for the presence
of Dubawnt erratics in till of Northern Manitoba. The northern
extent of the southerly flows lies immediately north of Schultz
Lake, east of Tehek Lake and across Wager Bay (Cunningham
and Shilts, 1977; McMartin and Dredge, 2005). Pervasive, opposite, early northward erosional forms and glacial dispersal have
been observed west of Committee Bay to the north (Phase I,
McMartin et al., 2003b). If these opposite flows were contemporaneous, we believe a dispersal centre or major ice divide
may have been positioned in Keewatin, between the study area
and Committee Bay, and across Wager Bay (Fig. 12). Based
on the robust nature of northward ice-flow indicators (i.e. roches
moutonnées and bedrock flutings), their consistent direction
over large areas, and their good preservation at high elevations,
Little (2001) and McMartin et al. (2003b) assigned a LGM timing for this northward phase west of Committee Bay. Kleman
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E
181
F
FIGURE 12. Phases of ice flow in central mainland Nunavut reconstructed from pre-deglacial and deglacial ice-flow sets (cf. Fig. 10) and
from available data in surrounding areas, and their relative age relationships. Proposed locations of ice divide positions are approximate.
Dashed flow lines are presumed relict, yet unrecognized in the literature. Ice stream flows are shown in blue. Ice marginal positions (dotted blue line) for Phases E (8.5 ka BP), F (8 ka BP) and G (7 ka BP)
are from Dyke (2004). Study area is outlined, as well as areas covered by recent GSC Quaternary mapping projects (dashed boxes).
Phases de l’écoulement glaciaire au centre du Nunavut continental
reconstituées à partir des familles d’écoulement glaciaire antérieur
et postérieur au retrait glaciaire (cf. fig. 10), et leur âge relatif. La localisation de l’emplacement des lignes de partage glaciaire est approximative. Les lignes d’écoulement tiretées sont présumées reliques,
mais elles ne sont pas encore documentées dans la littérature. Les
lignes d’écoulement associées à des courants de glace sont représentées en bleu. L’emplacement de la marge glaciaire (ligne pointillée bleue) pour les phases E (8.5 ka BP), F (8 ka BP) et G (7 ka BP)
sont tirées de Dyke (2004). La région à l’étude est délimitée ainsi que
les régions récemment étudiées par la Commission géologique du
Canada à travers des projets de cartographie du Quaternaire (boîtes
tiretées).
G
et al. (2002) positioned a dome in northern Keewatin by
73 ka BP based on old southerly striations (Tyrrell, 1897; Lee,
1959) and till lineations. Similarly, Boulton and Clark (1990b)
assigned an Early Wisconsinan age for south-southeasterly
flows from an early ice divide trending north-south in northern
Keewatin (Flow Stage B, p. 338). Without any evidence for relative ages, these authors assigned a later age for early, opposite northerly lineations (Flow set 5, Stage C1, p. 338). We argue
that the opposite spatial relationship between old southerly flows
in the study area and the northerly flows close to and north of
Wager Bay suggests these flows were part of the same phase,
yet of uncertain age. If the ice divide position we propose in
Keewatin during this Phase is valid, then it represents a southwestward movement of the ice divide by a minimum of 300 km.
PHASE C
This Phase represents an early advance of ice into the
region from an undetermined position in the Northwest
Territories (Fig. 12). If the eastward lineations regrouped into
Flow set 10 of Boulton and Clark (1990b) are of the same
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age, then it probably extended across the Back River Basin. In
addition, old eastward striations were found recently in the
higher Thelon River Basin as far west as longitude 104°
(Hardy, personal communication, 2004). This phase may be
responsible for the observation of scattered Dubwant erratics
and red till northeast of the Dubawnt dispersal train that straddles the study area (Nadeau and Schau, 1979; McMartin,
2000). Perhaps in parts of the Dubawnt train, the apparent
direction of southeastward dispersal also results from the
effects of southward dispersal reworked easterly. Dyke et al.
(1982) and Dyke and Prest (1987) proposed an ice dome west
of the study area (>500 km) during LGM with associated
east-southeastward flow lines, and postulated its eastward
migration into Keewatin from 12 to 9 ka BP. If the zone of maximum erosion is expected to move outward when an ice sheet
achieves maximum thickness (i.e. Boulton, 1996), then the
faded nature of the associated eastward ice-flow indicators
does uphold the hypothesis that this phase is of LGM age.
Alternatively, it may have occurred during ice-sheet build-up
prior to LGM, or as the ice sheet retreated after LGM.
PHASE D
The strong evidence for southeastward glacial transport in
the study area, in particular across the central axis of the
Keewatin Ice Divide (Zone 1 of Aylsworth and Shilts, 1989), as
well as the ubiquitous southeastward erosional ice-flow indicators, suggests Phase D was a major erosional phase in the
Keewatin region. Southeast flow must have been from a divide
first located northwest of the final position of the Keewatin Ice
Divide in order to bring Dubawnt clasts from the Baker Lake
Basin into the entire study area (Fig. 12), an idea first proposed
by Kaszycki and Shilts (1980, Keewatin Ice Divide position 3,
Fig. 6), and later by Klassen (1995) to explain the composition
of surficial deposits in the Pitz Lake area. The position of the
divide in Figure 12 is constrained by the lack of evidence for
southward transport of distinctive carbonate erratics in surface
till from a small Paleozoic outlier west of Schultz Lake
(Aylsworth and Shilts, 1989), by the up-ice limits of striations in
the Schultz Lake area, and by opposite directions of ice-flow
indicators within a narrow zone west of Wager Bay (McMartin
and Dredge, 2005). The western-most position of the divide is
not known although Boulton and Clark (1990b) placed a divide
with converging southeastward flows about 250 km northwest
of the position we propose here (Flow Stage D, p. 338). The
question of where streamlined landforms begin under an ice
divide produces the main difference between the two ice divide
positions. In addition, Boulton and Clark (1990b) used a group
of ‘south-southeast’ lineations north of Tehek Lake to gather
their ice divide position whereas detailed field work in this area
clearly indicates a north-northwestward ice flow (Utting and
McMartin, 2004). Besides, as discussed earlier, we believe the
convergent southeastward flows occurred much later during
deglaciation. The age of Phase D is not known, though it may
coincide with LGM or shortly after.
southeast by as much as 250 km from its last position in
Phase D (Fig. 12). The migration appears to have resulted
from the clockwise rotation of the divide to a more NNE-SSW
position, with the centre point stable in the uplands south of
Wager Bay as indicated by McMartin and Dredge (2005). This
flow is significant in that it implies that a zone of outflow existed
in the Kaminak-Kaminuriak Lakes area, southeast of the last
position of the Keewatin Ice Divide, and prior to the latest
southeastward flows in that area. Based on northward flowing
indicators measured along the northern shore of Yathkyed
Lake, Tyrrell (1897) defined the latest position of a centre of
outflow southeast of Yathkyed Lake during deglaciation. In
fact, this is probably the first phase that shows evidence for
deglaciation, at least for regions to the north of the study area.
As suggested by Boulton and Clark (1990a), the southeast
shift in the position of the divide conceivably reflects the progressive drawdown associated with development of flow
through Hudson Strait, and/or was triggered by the inception
of the Dubawnt Lake ice stream (their Flow Stage G1).
Near Tehek Lake, the latest flow is more northerly (Utting
and McMartin, 2004), and may represent the head of an ice
stream flowing northwestward in the Back River basin (Fig. 12),
perhaps forming a lobe in Queen Maud Golf at 8.5 ka BP
(Dyke, 2004). A northeastward ice flow into paleo-Committee
Bay (Phase II, McMartin et al., 2003b) may have been operating during this phase as the ice front retreated and formed a
calving bay in that area (9-8.5 ka BP, Dyke, 2004).
PHASE F
Between Phase E and this phase, the ice retreated to the
Chantrey Moraine System and the McAlpine Moraine at
8.2 ka BP (Dyke, 2004). The Dubawnt Lake ice stream was
operating in the Thelon River valley (Stokes and Clark, 2003),
extending back to areas close to the ice divide. After 8.2 ka BP,
the ice stream shut down, the ice front continued to retreat
easterly, and the ice divide probably began to migrate back
to the northwest as shown on Figure 12 at Phase F. North of
Wager Bay, the ice flow became more northerly, perpendicular to an ice front that is oriented into a general east-west configuration (Phase III, McMartin et al., 2003b). South of the
divide, the southeastward flow commenced to become convergent as a result of marine drawdown into a rapidly retreating calving front in Hudson Bay (8-7.7 ka BP, Dyke, 2004).
Deglaciation occurred over large areas in contact with deep
lakes or marine waters, producing a lobate ice sheet with
streamlined landforms fanning out to arcuate end moraines.
Boulton and Clark (1990a, 1990b) assumed the convergent
southeasterly-trending drift lineations in the area were middle
Wisconsinan in age, therefore occurring much before the
Dubawnt Lake ice stream. We showed evidence that the
convergent southeasterly ice flows operated time-transgressively as deglaciation proceeded across Keewatin.
PHASE G
PHASE E
Phase E indicates a major reversal of flow in the western
part of the study area as the ice divide migrated towards the
Between about 8 and 7 ka BP, the ice front retreated significantly as the marine calving bay moved up rapidly into
Hudson Bay, leading to the splitting of the ice sheet in two
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EVIDENCE FROM KEEWATIN (CENTRAL NUNAVUT) FOR PALEO-ICE DIVIDE MIGRATION
masses on either side of Hudson Strait (Dyke, 2004). The final
position of the ice divide depicted on Figure 12 at Phase G
lies across Yathkyed Lake, Pitz Lake, the western part of Baker
Lake, and over the uplands south of Wager Bay. It indicates a
northwestward shift of about 100 km from the position at
Phase E. In the study area and within the Schultz Lake map
sheet to the north, the ice divide position is constrained by
the limit of late southeastward ice-flow indicators. This is the
position that has been shown in previous maps and reports
(Cunningham and Shilts, 1977; Shilts et al., 1979; Shilts,
1980a; Aylsworth and Shilts, 1989) as the location of the
Keewatin Ice Divide sensu stricto. After 7 ka BP, the remaining
ice mass, covering basically the Keewatin Ice Divide Zone 1 of
Aylsworth and Shilts (1989), is further split in two small
masses on either side of Chesterfield Inlet as the sea invades
the Thelon River valley before final deglaciation after 6.5 ka BP
(Dyke, 2004).
SIGNIFICANCE OF RELICT GLACIAL LANDSCAPE
BENEATH THE KEEWATIN ICE DIVIDE
The widespread preservation of crosscutting glacial erosional forms (striae, grooves, roches moutonnées, etc.) and
ice-moulded landforms in central Nunavut reflects a sequence
of regional ice-flow events of different directions at different
times. This study shows that the most recent ice-flow events
have not destroyed all evidence of previous ice-flow directions,
particularly in the glacial erosional record. As many as five discrete orientations of striations are preserved at several sites
in the area close to the Keewatin Ice Divide (cf. Zone 1 of
Aylsworth and Shilts, 1989). The profusion of opposed and
superimposed streamlined forms beneath the former ice divide
is indicative of ice flowing from considerably different directions, distinct from those associated with the last position of
the Keewatin Ice Divide. Aylsworth and Shilts (1989) suggested
the constructional landforms within and around the former ice
divide were related to ice flowing from the divide during much
of the last glaciation. Alternatively, we believe that much of the
glacial landscape under the former Keewatin Ice Divide relates
to older flows, and that the coexistence of ice directional indicators of different orientation throughout the study area reflects
the transitory nature of ice divide(s) in the region.
Given that horizontal ice velocity, and therefore glacial erosion, is minimal under ice divides (e.g. Benn and Evans,
1998), it has been suggested that deformation of landforms by
multiple flows can only occur at some distance from an ice
divide (Clark, 1993). Close to or beneath the former Keewatin
Ice Divide, within a zone of a minimum of 150 km in width, we
find evidence for a range of subglacial modification of landforms from the intact survival of pre-existing landforms, to
superimposed landforms, to strong deformation where the
most recent lineations become dominant. With increasing distance from this zone, the landforms predominantly reflect the
last ice-flow patterns and only isolated relict bedforms are
found, unless the abundant ribbed moraines in this area are
interpreted as the result of crossing drift lineations (e.g.
Boulton, 1987). If we follow Clark’s argument that the ice-flow
velocity may be the main determinant of the degree of deformation, then the observed continuum of landforms indicates
183
significant changes in flow velocity that can only be obtained
by migrating ice divide(s).
Boulton and Clark (1990a, 1990b) suggested that areas
covered by the Laurentide Ice Sheet with a large number of
glacial lineations reflect less intense glacial erosion and debris
transport, and correspond to general locations of migrating
ice divides. In the study area, the complex record of smallscale erosional forms and the evidence for attenuated opposing ice-flow indicators, along with relict landforms and relict
deposits, imply that both erosion and deposition were occurring at various times during glaciation. While Kaszycki and
Shilts (1980) also envisioned the idea of alternating erosiondeposition under active ice, they did not invoke significant
changes in the position of ice divides and flow patterns. In the
Keewatin region, the major shifts observed in ice-flow directions, the multiple-till stratigraphy along the Kazan and Thelon
Rivers, and patterns of glacial dispersal to some extent, are
compatible with proximity to a migrating ice divide, and suggest there was a major input of subglacial sediment for some
of the ice-flow events, while for others there was probably no
input but only minor erosion/deformation of existing surfaces.
On the other hand, shifts in ice flow were probably occurring
too rapidly for total reorganisation of the bed, or for a gradual
change in the direction of ice flow. Rapid shifts in ice flow separated by periods of relative stability could explain the occurrence of ice-flow indicators in discrete sets (e.g. Clark, 1993).
Boulton and Clark (1990a, 1990b) also suggested that the
basal zone of little or no basal flow can be up to 200 km wide
under dispersal centres and that no significant glacial lineations can occur in this zone. For that reason they proposed
that the appearance of the Keewatin Ice Divide was a bogus
feature produced by the use of lineations of different ages to
define the divide, and by the migration of the divide (Boulton
and Clark, 1990a; Fig. 16). Alternatively, we suggest that the
absence of eskers over the divide zone and the radial pattern
of eskers and ribbed moraine around the Keewatin Ice Divide
strongly argues against a false ice divide position. Moreover,
similar to that reported in contemporary ice sheets near ice
divides (i.e. Wilch and Hughes, 2000), flowlines probably
extended nearly to the ice drainage divide, as recorded by
striation limits and to some extent by corresponding landforms.
Although basal shear stresses are known to be small near ice
divides, Pettit et al. (2003) recently suggested longitudinal
stresses (pulling effect of down-stream ice) in present-day
warm-based ice can be significant and can control basal sliding velocity in these areas. Therefore, although we observed
old glacial landforms preserved beneath the divide zone, we
argue that the Keewatin Ice Divide Zone 1 of Aylsworth and
Shilts (1989) is a reasonable approximation of the last position
of the central axis of the divide, as opposed to the “general
position throughout the last glaciation” (Aylsworth and Shilts,
1989: p. 3).
SUMMARY
An ice-flow sequence was reconstructed in the Keewatin
region of central Nunavut through the careful mapping and
correspondence over broad areas of striae and glacial landforms. The sequence of paleo-ice flows presented herein
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I. MCMARTIN and P. J. HENDERSON
shows that a zone of outflow within the Laurentide Ice Sheet
existed in Keewatin, possibly through much of its Wisconsinan
history, as originally proposed by Tyrrell (1897) and later by
Shilts (1980a). Nonetheless, the observation of multi-faceted
and cross-striated outcrops, palimpsest streamlined landforms
and stacked tills of distinct provenance in the study area indicates shifting ice-flow centres, where relatively slight shifts in
either the configuration or location of the zone of outflow, or
both, produced drastic changes in ice-flow directions.
The record of successive flows suggests that a divide
shifted several times in different directions in Keewatin, by as
much as 500 km between phases, prior to the final decay of the
LIS towards its last position. Earlier imprints of glacial flow were
modified and overprinted by the younger ice-flow patterns but
the patterns of cross-cutting ice-flow sets document the evolving geometry of the ice sheet that generated them. The relict
glacial landscape underneath the Keewatin Ice Divide Zone 1
of Aylsworth and Shilts (1989) reflects protection under the ice
divide because of low-velocity basal sliding, and changes in
flow velocity as a result of ice divide migration.
A sequence of seven distinct regional phases of ice flow
was established in the Keewatin region from Phase A, which
probably occurred prior to LGM, during the Early Wisconsinan
or perhaps prior to the last glaciation, to Phase G before final
deglaciation. Flows during Phases A and C were probably from
ice centres external to the region. The others stemmed from
local ice centres and divides in central Nunavut, and particularly
from the Keewatin Ice Divide area from Phase D through
deglaciation. The discordances in flow direction during the last
deglacial flows into Hudson Bay suggest the convergent southeasterly flows continuously operated during margin retreat.
This work argues against a stable Keewatin Ice Divide
throughout the Wisconsinan glaciation, and lays the foundation
for a new and revised glacial history for the Keewatin Sector
of the Laurentide Ice Sheet. The work also questions previous interpretations of large erratic dispersal patterns, such as
the Dubawnt dispersal train, and provides a framework for
understanding glacial dispersal trains from mineralized
bedrock, and, consequently, has important implications for
mineral exploration in the Keewatin region.
REFERENCES
Andrews, J.T., 1987. The Late Wisconsinan glaciation and deglaciation of the
Laurentide Ice Sheet, p. 12-37. In W.F. Ruddiman and H.E. Wright Jr., eds.,
North America and Adjacent Oceans During the Last Deglaciation, Geology of
North America, K-3. Geological Society of America, Boulder, Colorado, 501 p.
Arsenault, L., Aylsworth, J.M., Kettles, I.M. and Shilts, W.W., 1981. Surficial
geology, Kaminak Lake, District of Keewatin. Geological Survey of Canada,
Ottawa, Map 7-1979, Scale 1:125 000.
Aylsworth, J.M., Boydell, A.N., Cunningham, C.M. and Shilts, W.W., 1981a.
Surficial geology, MacQuoid Lake, District of Keewatin. Geological Survey
of Canada, Ottawa, Map 11-1980, Scale 1:125 000.
Aylsworth, J.M., Boydell, A.N. and Shilts, W.W., 1981b. Surficial geology, Tavani,
District of Keewatin. Geological Survey of Canada, Ottawa, Map 9-1980,
Scale 1:125 000.
Aylsworth, J.M., Boydell, A.N. and Shilts, W.W., 1981c. Surficial geology, Marble
Island, District of Keewatin. Geological Survey of Canada, Ottawa, Map
10-1980, Scale 1:125 000.
Aylsworth, J.M., Boydell, A.N. and Shilts, W.W., 1984. Surficial geology, Gibson
Lake, District of Keewatin. Geological Survey of Canada, Ottawa, Map
1-1984, Scale 1:125 000.
Aylsworth, J.M., Boydell, A.N. and Shilts, W.W., 1986. Surficial geology,
Chesterfield Inlet, District of Keewatin. Geological Survey of Canada,
Ottawa, Map 1-1985, Scale 1:125 000.
Aylsworth, J.M., Cunningham, C.M. and Shilts, W.W., 1981d. Surficial geology,
Ferguson Lake, District of Keewatin. Geological Survey of Canada, Ottawa,
Map 2-1979, Scale 1:125 000.
Aylsworth, J.M., Cunningham, C.M. and Shilts, W.W., 1989. Surficial geology,
Thirty Mile Lake, District of Keewatin, Northwest Territories. Geological
Survey of Canada, Ottawa, Map 39-1989, Scale 1:125 000.
Aylsworth, J.M. and Shilts, W.W., 1989. Glacial features around the Keewatin Ice
Divide: Districts of Mackenzie and Keewatin. Geological Survey of Canada,
Ottawa, Paper 88-24, 21 p.
Benn, D.I. and Evans, D.J.A., 1998. Glaciers and Glaciation. Oxford University
Press, New York, 734 p.
Boulton, G.S., 1987. A theory of drumlin formation by subglacial sediment deformation, p. 75-80. In J. Menzies and J. Rose, eds., Drumlin Symposium.
Balkema, Rotterdam, 360 p.
Boulton, G.S., 1996. Theory of glacial erosion, transport and deposition as a
consequence of subglacial sediment deformation. Journal of Glaciology,
42 : 43-62.
Boulton, G.S. and Clark, C.D., 1990a. A highly mobile Laurentide ice sheet
revealed by satellite images of glacial lineations. Nature, 346 : 813-817.
Boulton, G.S. and Clark, C.D., 1990b. The Laurentide ice sheet through the last
glacial cycle: the topology of drift lineations as a key to the dynamic behaviour of former ice sheets. Transactions of the Royal Society of Edinburgh, 81 :
327-347.
Boulton, G.S., Smith, G.D., Jones, A.S. and Newsome, J., 1985. Glacial geology
and glaciology of the last mid-latitude ice sheets. Journal of the Geological
Society of London, 142 : 447-474.
ACKOWLEDGEMENTS
This work was carried out as part of the Western Churchill
NATMAP Program in 1997-2002, and the Western Churchill
Metallogeny Project (Y12-NR4550) under the Northern
Resources Development Program of Natural Resources
Canada (http://nrd.nrcan.gc.ca). We are grateful to S. Khan, W.
Carter and C. St-Pierre for assistance in the field, and to the
GSC and INAC bedrock mapping groups for sharing logistics
and mapping expertise in 1997, 1998 and 1999 (S. Hanmer,
D. Irwin, R. Rainbird, C. Relf and S. Tella). The authors would
also like to acknowledge Polar Continental Shelf Project for
providing invaluable helicopter support. Thanks are extended
to Tracy Barry for preparing some of the figures, and to Lynda
Dredge and two anonymous reviewers for useful comments on
an earlier draft of the manuscript.
Clark, C.D., 1993. Mega-scale glacial lineations and cross-cutting ice-flow landforms. Earth Surface Processes and Landforms, 18 : 1-29.
Clark, C.D., 1994. Large-scale ice moulding: a discussion of genesis and glaciological significance. Sedimentary Geology, 91 : 253-268.
Clark, C.D., 1997. Reconstructing the evolutionary dynamics of former icesheets using multi-temporal evidence, remote sensing and GIS. Quaternary
Science Reviews, 16 : 1067-1092.
Clark, C.D., 1999. Glaciodynamic context of subglacial bedform generation and
preservation. Annals of Glaciology, 28 : 23-32.
Clark, C.D., Knight, J.K. and Gray, J.T., 2000. Geomorphological reconstruction
of the Labrador Sector of the Laurentide Ice Sheet. Quaternary Science
Reviews, 19 : 1343-1366.
Clark, P.U., Licciardi, J.M., MacAyeal, D.R. and Jenson, J.W., 1996. Numerical
reconstruction of a soft-bedded Laurentide Ice Sheet during the last glacial maximum. Geology, 24 : 679-682.
Géographie physique et Quaternaire, 58(2-3), 2004
GPQ_58-2-3.qxd
20/06/06
09:53
Page 185
EVIDENCE FROM KEEWATIN (CENTRAL NUNAVUT) FOR PALEO-ICE DIVIDE MIGRATION
Coker, W.B., Spirito, W.A., DiLabio, R.N.W. and Hart, B.R., 1992. Geochemistry
(till, gossan and lake sediment-AU and PGE) and surficial geology of the
Ferguson, Yathkyed and Contwoyto Lakes areas, NWT, p. 93-97. In D.G.
Richardson and M. Irving, eds., Project Summaries: Canada-Northwest
Territories Mineral Development Subsidiary Agreement 1987-1991.
Geological Survey of Canada, Ottawa, Open File 2484, 248 p.
Craig, B.G. and Fyles, J.G., 1960. Pleistocene geology of Arctic Canada.
Geological Survey of Canada, Ottawa, Paper 60-10, 21 p.
Cunningham, C.M. and Shilts, W.W., 1977. Surficial geology of the Baker Lake
area, District of Keewatin. Geological Survey of Canada, Ottawa, Report
on Activities B : 311-314.
DiLabio, R.N.W., 1979. Drift prospecting in uranium and base-metal mineralization sites, District of Keewatin, Northwest Territories, Canada, p. 91-100.
In Prospecting in areas of glaciated terrain. Institute of Mining and
Metallurgy, London, 109 p.
Dyke, A.S., 2004. An outline of North American deglaciation with emphasis on
central and northern Canada, p. 373-424. In J. Ehlers and P.L. Gibbard,
eds., Quaternary Glaciations: Extent and Chronology, Part II. Elsevier,
Amsterdam, 440 p.
Dyke, A.S., Andrews, J.T., Clark, P.U., England, J.H., Miller, G.H., Shaw, J. and
Veillette, J.J., 2002. The Laurentide and Innuitian ice sheets during the Last
Glacial Maximum. Quaternary Science Reviews, 21 : 9-31.
Dyke, A.S., Dredge, L.A. and Vincent, J.-S., 1982. Configuration and dynamics
of the Laurentide Ice Sheet during the Late Wisconsin Maximum.
Géographie physique et Quaternaire, 36 : 5-14.
Dyke, A.S. and Prest, V.K., 1987. Paleogeography of northern North America,
18 000-5 000 years ago. Geological Survey of Canada, Ottawa, Map 1703A,
Scale 1:12 500 000.
Environment Canada, 1986. Hydrometric Map Supplement. Inland Waters
Directorate, Water Resources Branch, Water Survey of Canada, Ottawa.
Flint, R.F., 1943. Growth of the North American ice sheet during the Wisconsin
Age, Geological Society of America, Bulletin 54, p. 325-362.
Gall, Q., Peterson, T.D. and Donaldson, J.A., 1992. A proposed revision of Early
Proterozoic stratigraphy of the Thelon and Baker Lake basins, Northwest
Territories. Geological Survey of Canada, Ottawa, Current Research, Part
C :129-137.
Hadlari, T., Rainbird, R.H. and Pehrsson, S.J., 2004. Geology, Schultz Lake,
Nunavut. Geological Survey of Canada, Ottawa, Open File 1839, Scale
1:250 000.
Henderson, P.J., 2000. Drift composition and surficial geology, MacQuoid Lake
area (NTS 55M/7 and 55M/10), Keewatin region, Nunavut: a guide to drift
prospecting. Geological Survey of Canada, Ottawa, Open File 3944, 189 p.
Kaszycki, C.A. and Shilts, W.W., 1979. Average depth of glacial erosion,
Canadian shield. Geological Survey of Canada, Ottawa, Current Research,
Part B : 395-396.
Kaszycki, C.A. and Shilts, W.W., 1980. Glacial erosion of the Canadian Shieldcalculation of average depths. Atomic Energy of Canada Limited, Technical
Record TR-106, 37 p.
Klassen, R.A., 1995. Drift composition and glacial dispersal trains, Baker Lake
area, District of Keewatin, Northwest Territories. Geological Survey of
Canada, Ottawa, Bulletin 486, 68 p.
Klassen, R.A., 2001. The interpretation of background variation in regional geochemical surveys: an example from Nunavut, Canada. Geochemistry:
Exploration, Environment, Analysis, 1-2 : 163-173.
Kleman, J., 1990. On the use of glacial striae for reconstruction of paleo-ice
sheet flow patterns. Geografiska Annaler, Series A-Physical Geography,
72 : 217-236.
Kleman, J., Borgström, I. and Hättestrand, C., 1994. Evidence for a relict glacial
landscape in Quebec-Labrador. Palaeogeography, Palaeoclimatology,
Palaeoecology, 111 : 217-228.
Kleman, J., Fastook, J. and Stroeven, A.P., 2002. Geological and geomorphologically constrained numerical model of Laurentide Ice Sheet inception
and build-up. Quaternary International, 95-96 : 87-98.
Lee, H.A., 1959. Surficial geology of southern District of Keewatin and the
Keewatin Ice Divide, Northwest Territories. Geological Survey of Canada,
Ottawa, Bulletin 51, 42 p.
185
Lee, H.A., Craig, B.G. and Fyles, J.G., 1957. Keewatin Ice Divide. Geological
Society of America Bulletin, 68 : 1760-1761.
Little, E. C., 2001. Preliminary results of relative ice-movement chronology of the
Laughland Lake map area, Nunavut. Geological Survey of Canada, Ottawa,
Current Research 2001-C14, 12 p.
Lord, C.S., 1953. Geological notes on the Southern District of Keewatin.
Geological Survey of Canada, Ottawa, Paper 53-22, 11 p.
Lundqvist, J., 1990. Glacial morphology as an indicator of the direction of glacial transport, p. 61-70. In R. Kujansuu and M. Saarnisto, eds., Glacial
Indicator Tracing. Balkema, Rotterdam, 252 p.
Marshall, S.J., James, T.S. and Clarke, G.K.C., 2002. North American Ice Sheet
reconstructions of the Last Glacial Maximum. Quaternary Science Reviews,
21 : 175-192.
McMartin, I., 2000. Till composition across the Meliadine Trend, Rankin Inlet
area, Keewatin Region, Nunavut. Geological Survey of Canada, Ottawa,
Open File 3747, 329 p.
McMartin, I. and Dredge, L.A., 2005. History of ice flow in the Schultz Lake
(NTS 66A) and Wager Bay (NTS 56G) areas, Kivalliq Region, Nunavut.
Geological Survey of Canada, Ottawa, Current Research 2005-B-2, 10 p.
McMartin, I., Dredge, L.A., Ford, K. and Kjarsgaard, I., 2006. Till composition,
provenance and stratigraphy beneath the Keewatin Ice Divide, Schultz Lake
area (NTS 66A), mainland Nunavut. Geological Survey of Canada, Ottawa,
Open file 5312, 1 CD-ROM.
McMartin, I. and Henderson, P.J., 1999. A relative ice-flow chronology for the
Keewatin Sector of the Laurentide Ice Sheet, Northwest Territories (Kivalliq
Region, Nunavut). Geological Survey of Canada, Ottawa, Current Research
1999-C :129-138.
McMartin, I. and Henderson, P.J., 2004. Ice flow history and glacial stratigraphy,
Kivalliq Region, Nunavut (NTS 55K,J,L,M,N,O; 65I and P): complete
datasets, maps and photographs from the Western Churchill NATMAP
Project. Geological Survey of Canada, Ottawa, Open File 4595, 1 CD-ROM.
McMartin, I., Henderson, P.J., Kjarsgaard, B.A. and Venance, K., 2003a.
Regional distribution and chemistry of kimberlite indicator minerals, Rankin
Inlet and MacQuoid Lake areas, Kivalliq Region, Nunavut. Geological Survey
of Canada, Ottawa, Open File 1575, 110 p.
McMartin, I., Little, E.C., Ferbey, T., Ozyer, C.A. and Utting, D.J., 2003b. Ice flow
history and drift prospecting in the Committee Bay belt, central Nunavut:
results from the Targeted Geoscience Initiative. Geological Survey Canada,
Ottawa, Current Research 2003-C4, 11 p.
Mitchell, W.A., 1994. Drumlins in ice sheet reconstructions, with reference to the
western Pennines, northern England. Sedimentary Geology, 91 : 313-331.
Nadeau, L. and Schau, M., 1979. Surficial geology near the mouth of the Quoich
River, District of Keewatin. Geological Survey of Canada, Ottawa, Current
Research Part A : 389-390.
Paul, D., Hanmer, S., Tella, S., Peterson, T.D. and LeCheminant, A.N., 2002.
Compilation, bedrock geology of part of the western Churchill Province,
Nunavut-Northwest Territories. Geological Survey of Canada, Ottawa, Open
File 4236, Scale 1:1 000 000.
Peltier, W.R., 1996. Mantle viscosity and ice-age ice-sheet topography. Science,
273 : 1359-1364.
Pettit, E.C., Jacobson, H.P. and Waddington, E.D., 2003. Effects of basal sliding
on isochrones and flow near an ice divide. Annals of Glaciology, 37 : 370-376.
Prest, V.K., 1970. Quaternary geology of Canada, p. 676-764. In R.J.W. Douglas,
ed., Geology and Economic Minerals of Canada. Geological Survey of
Canada, Ottawa, Economic Geology Report No. 1, 838 p.
Prest, V.K., Grant, D.R. and Rampton, V.N., 1968. Glacial Map of Canada,
Geological Survey of Canada, Ottawa, Map 1253A, Scale 1:5 000 000.
Repo, R., 1954. Om forhallandet mellan rafflor och asar (on the relationship
between eskers and striae). Geologi, 6 : 45.
Ridler, R H. and Shilts, W.W., 1974. Exploration for Archean polymetallic sulphide
deposits in permafrost terrains, Kaminak Lake area, District of Keewatin.
Geological Survey of Canada, Ottawa, Paper 73-34, 33 p.
Schau, M., 1981. Direction of movement of glacially transported boulders not
necessarily shown by preserved ice-movement direction indicators, Baker
Lake, District of Keewatin. Geological Survey of Canada, Ottawa, Current
Research, Part A : 383.
Géographie physique et Quaternaire, 58(2-3), 2004
GPQ_58-2-3.qxd
20/06/06
09:53
Page 186
186
I. MCMARTIN and P. J. HENDERSON
Shilts, W.W., 1971. Trace element and mineral indicator tracing, Kaminak Lake,
District of Keewatin. Geological Survey of Canada, Ottawa, Paper 71-01A-:
191-192.
Shilts, W.W., 1973. Drift prospecting; geochemistry of eskers and till in permanently frozen terrain: District of Keewatin; Northwest Territories. Geological
Survey of Canada, Ottawa, Paper 72-45, 34 p.
Shilts, W.W., 1977. Geochemistry of till in perennially frozen terrain of the
Canadian Shield – application to prospecting. Boreas, 5 : 302-212.
Shilts, W.W., 1980a. Flow patterns in the central North American ice sheet.
Nature, 286 : 213-218.
Shilts, W.W., 1980b. Geochemical profile of till from Longlac, Ontario to Somerset
Island. Canadian Institute of Mining Bulletin, 73 : 85-94.
Shilts, W.W., 1986. Glaciation of the Hudson Bay region, p. 55-78. In I.P. Martini,
ed., Canadian Inland Seas, Elsevier, Amsterdam, 494 p.
Shilts, W.W., Cunningham, C.M. and Kaszycki, C.A., 1979. Keewatin Ice SheetRe-evaluation of the traditional concept of the Laurentide Ice Sheet. Geology,
7 : 537-541.
Stokes, C.R. and Clark, C.D., 2003. The Dubawnt Lake palaeo-ice stream: evidence for dynamic ice sheet behaviour on the Canadian Shield and insights
regarding the controls on ice-stream location and vigour. Boreas, 32 :
263-279.
Tarasov, L. and Peltier, R.W., 2004. A geophysically constrained large ensemble analysis of the deglacial history of the North American ice-sheet complex. Quaternary Science Reviews, 23 : 359-388.
Taylor, R.S., 1956. Glacial geology of north-central Keewatin, Northwest
Territories, Canada. Bulletin of the Geological Society of America, 67 :
943-956.
Tyrrell, J.B., 1897. Report on the Doobaunt, Kazan, and Ferguson rivers and the
northeast coast of Hudson Bay. Geological Survey of Canada, Ottawa,
Annual Report 618 : 1F-218F.
Utting, D.J. and McMartin, I., 2004. Ice-movement indicator mapping north of the
Keewatin Ice Divide, Meadowbank area, Nunavut. Geological Survey of
Canada, Ottawa, Current Research 2004-C8, 6 p.
Veillette, J.J., Dyke, A.S. and Roy, M., 1999. Ice-flow evolution of the Labrador
Sector of the Laurentide Ice Sheet: a review, with new evidence from northern Quebec. Quaternary Science Reviews, 18 : 993-1019.
Stea, R.R., 1994. Relict and palimpsest glacial landforms in Nova Scotia,
Canada, p. 141-148. In W.P. Warren and D.C. Groots, eds., Proceedings of
the Commission on the Formation and Deformation of Glacial Deposits,
Dublin, Ireland, May 1991, Balkema, Rotterdam, 223 p.
Wilch, E. and Hughes, T.J., 2000. Calculating basal thermal zones beneath the
Antarctic ice sheet. Journal of Glaciology, 46 : 297-310.
Stea, R.R. and Brown, Y., 1989. Variation in drumlin orientation, form and stratigraphy relating to successive ice flows in southern and central Nova Scotia.
Sedimentary Geology, 62 : 223-240.
Wright, G.M., 1967. Geology of the southeastern barren grounds, parts of the
Districts of Mackenzie and Keewatin. Geological Survey of Canada, Ottawa,
Memoir 350, 91 p.
Géographie physique et Quaternaire, 58(2-3), 2004